The basic design of the body allows a wide range of variation of most functions under stress, yet even this range becomes inadequate in acute states. The basic objective of this research project is to study the systems design and function of the body with emphasis on the destructive processes instituted by exceeding the physiological limits of systems. Two systems are of immediate interest. Present evidence indicates that the centrilobular liver cells swell from hypoxia in low blood flow states, block sinusoidal blood flow and cause the "bloody diarrhea" syndrome in shock. Hemodynamic analysis and bypass shunting will be used to "prove" the idea. Also, the energy system of the body loses its chemical base during hypoxia. Direct measurement of purine in various tissues will be used to determine local and zonal areas of an organ damaged by low blood flow states. Computer analysis of control systems will also be used to determine limits of physiological performance.